The game have to be lock at 60 FPS maximum, above that it will break the game speed and also the in game timer.

Example :

That's strange. Didn't even notice the igt was broken.
Ah well. Happens

I don't know a lot of softwares who can lock FPS, but there is Fraps even if it's pretty old. I'm guessing it's caused by FPS that could also be hardware, i know that some recent processors speed up some old games sometimes.

I picked up the game recently, and I play at more than 60fps (checked this with RivaTuner Statistics while FPS weren't locked) but the game's speed doesn't seem broken at all on PC. Timer is consistent with an external timer even at 300+ fps. I think this needs a bit more of documentation.

Just checked this. No difference between 60fps and 160+ i got it to run at. Tested at Alpine 2, Same car, automatic with full throttle until crashing into the wall. Both hit the wall on exact same frame in the recordings.

Not sure what caused the difference in timer for lonne then (maybe vsync off ?), i guess if the rta and igt timer of the player are fine the rule of FPS limit could be removed.